What the cell surface does not see: the gene vector under the protein corona

The fate of lipid-based nanovectors, used in genetic targeting inside cells, depends on their behavior in biological media. In fact, during both in vitro and in vivo transfection, nanovectors come in contact with proteins that compete for their surface and build the protein corona, their true biological identity while engaging the cell membrane. Nonetheless, after cell internalization, the efficacy of transfection may depend also on structural modifications that occurred under the protein cover, following interaction with biological fluids. Here, based on previous in vivo experiments, two widely used lipid mixtures, namely DOTAP/DOPC and DC-Chol/DOPE, were identified as paradigms to investigate the impact of the inner structure of nanovectors on the transfection efficiency, all being proficiently internalized. The evolution of the inner structure of cationic lipoplexes and nanoparticles based on such lipid mixtures, following interaction with human plasma, could be unraveled. Particles were investigated in high dilution, approaching the biosimilar conditions. Data have demonstrated that the modulation of their inner structure depends on their lipid composition and the plasma concentration, still preserving the genetic payload. Interestingly, protein contact induces a variety of inner structures with different perviousness, including reshaping into cubic phases of different porosity, sometimes observed upon interaction between carrier-lipids and cell-lipids. Cubic reshaping is of biological relevance, as lipid cubic phases have been recently associated to both fusogenicity and to the readiness in releasing the payload to the final target via endosomal escape.